Intl Scout 6.2 ATS Turbo help needed

[HRSPOWR]

I have a 77 Scout that I swapped in a 6.2 700r4 setup out of an 84 Suburban.
3.55 gears, 33" tires. Rig weighs about 5000 lbs.

Runs GREAT, pleanty of power, lots of fun to drive, but I expected a little better mileage. Driving carefully, no stomping gas, etc, I get 10-11mpg.

Previous suburban owner had a Goodwrench engine installed approx, 70k ago. He also added an ATS turbo system.

During the conversion I beefed up the 700r4, turned up the pump about an 1/8th of a turn, I get no black smoke... Ever.

My pump advance is about a 1/8" past the factory mark towards the driver side. My cold advance is on a switch, and when cruising, if I flip the switch (with fast idle disconnected) there is a noticable surge forward, and boost gauge jumps by 2-3 PSI. (My ATS doesn't run boost unless I really step on it, and maxes out about 5-6 pounds)

It runs really well with cold advance on, but has funny throttle response, seems to surge, and builds psi twice as fast as normal.

I don't have access to a timing setup for diesels, so am trying to figure out by seat of pants.

by how it runs with Cold advance on, I would think it needs more advance?

I bumped it another lines worth, isnt that much louder, still runs great, but still works tons better when I flip advance switch.

Im I fooling myself that I can get better then 15mpg with this combo?


Thanks for any help you can provide.


Dan

[john8662]

Part-time or full time 4x4?

How accurate is the speedometer/odometer combination?

J

[HRSPOWR]

Speedo is right on according to GPS.

Part time 4x4, hubs are unlocked.

This is a flying brick, no aerodynamics, so that's part of it, but thought I would get better mpg.

[HRSPOWR]

Kinda at a loss.


Think I will crank the timing a little and see what happens.

[Robyn]

My guess is that the Goodwrench engine is a 6.5 and not a 6.2

GM started using the 6.5 crate engine across the board as a replacement.

The pecups are not the same as the ones used in the 6.2 engines of the 80's and the 6.5 does not get the 20+ mpg that the 6.2 did

You should be able to get better than 11 though.

Timing is very important and you really need to get the timing spot on.

Missy

[Subzilla]

My '83 3/4 ton Sub has 4.10 gear, 35" tires, 4x4, 6.2, ATS turbo and (prior to broken crankshaft) was consistently getting 17 mpg. When I added the turbo, I put 6.5 heads on it. Without a trailer, I could see 6 maybe boost pounds but could spike up to 10 when pulling a trailer. Even when puller a pop-up or 2 horse trailer, I never saw worse than 15.5.

Follow Robyn's advice.

[HRSPOWR]

Hmmmm,

Never considered that it might be a 6.5

Will look at telling difference by casting number or something.


I think the ATS probably needs to be rebuilt, as there are no restrictions in exhaust or anything to stop boost.

Will have to see if I can find a local shop that can help me get timing right.

Thanks!